Method for producing fire-resistant polymeric material and fire-resistant polymeric material
Extrusion mixing of PFA with EVA at controlled conditions addresses the challenge of achieving high fire resistance and deformability in polymeric materials, enabling a material with up to 80% PFA content and improved mechanical properties.
Patent Information
- Authority / Receiving Office
- RU · RU
- Patent Type
- Patents
- Current Assignee / Owner
- FEDERALNOE GOSUDARSTVENNOE BYUDZHETNOE UCHREZHDENIE NAUKI FEDERALNYJ ISSLEDOVATELSKIJ TSENTR KHIMICHESKOJ FIZIKI IM N N SEMENOVA ROSSIJSKOJ AKADI NAUK FITS KHF RAN
- Filing Date
- 2025-07-04
- Publication Date
- 2026-07-09
AI Technical Summary
Existing methods for producing fire-resistant polymeric materials face challenges in achieving high fire resistance while maintaining high deformability and mechanical properties, particularly when increasing the content of flame retardants like ammonium polyphosphate beyond certain limits.
A method involving extrusion mixing of a melt of ammonium polyphosphate (PFA) with ethylene vinyl acetate (EVA) at controlled temperatures and screw speeds, allowing for a higher PFA content up to 80 wt.%, resulting in a material with enhanced fire resistance and deformability.
The method achieves fire resistance up to 95% and maintains high deformability, surpassing current materials by ensuring both high fire resistance and mechanical integrity.
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Abstract
Description
[0001] The invention relates to flame-retardant polymeric materials that do not spread flames based on thermoplastic ammonium polyphosphates (PFA) and can be used in the production of household equipment, cables, building materials, and in electrical engineering and electronics.
[0002] Foaming fire-protective coatings based on PFA and low-flammability polymeric materials are known, containing phosphates and polyphosphates as a filler, which, upon thermal exposure, form a barrier layer of polyphosphoric acid on the surface of the organic polymer phase, which has low volatility and prevents the diffusion of oxygen from the external environment into the combustion zone (Nenahov S.A., Pimenova V.P. Physicochemistry of foaming fire-protective coatings based on ammonium polyphosphate. Fire and Explosion Safety, 2010. Vol. 19, No. 8, pp. 11-57).
[0003] PFA-based compositions are known for obtaining fire-protective foaming coatings for wood, metals, and concrete, both on organic solvents (RU 2186813, 10.08.2002) or epoxy resins (RU 2199564, 27.02.2003; RU 2224775, 27.02.2004), and on an aqueous medium (USSR Author's Certificate No. 902450, published 30.07.1986; US 11679290, 20.06.2023).
[0004] A fire-resistant polymer material for structural applications is known, produced by dry mixing of components in powder form. The material contains ultra-high molecular weight polyethylene and PFA with a degree of polymerization of at least 1200 at a mass ratio of UHMWPE to PFA = 4:1 (RU 2350642, March 27, 2009).
[0005] A fire-resistant polymer material based on a thermoplastic elastomer containing a multicomponent phosphorus-containing flame retardant is known. The content of the multicomponent flame retardant in the material is declared in an amount of 5 to 60 wt. %, preferably from 10 to 40 wt. %, - in all examples 45 wt. %. The basis of the multicomponent phosphorus-containing flame retardant is PFA in crystalline modification II, n> 1000 (FR CROS 489, etc.), the PFA content in the material according to the examples is 34 wt. %. To obtain the material, the polymer is melted in a Brabender mixer and, while stirring, the multicomponent flame retardant is added to the melt either as a mixture of components, or all the components of the flame retardant sequentially. The oxygen index (II) of the material is 28-34% (RU 2490287, 20.08.2013).
[0006] The closest to the proposed method for producing a fire-resistant polymeric material and the fire-resistant polymeric material obtained by this method are the method for producing a fire-resistant polyolefin material based on an intumescent phosphorus-containing fire retardant and the polyolefin material based on an intumescent phosphorus-containing fire retardant, described in US application US 20150111986, 04 / 23 / 2015 (prototype).
[0007] The prototype method for producing a flame-retardant polyolefin material uses a single-screw or twin-screw extruder to mix the components. The organic polymer is pre-injected into the extruder, and the temperature is raised to a temperature sufficient to melt it. All other components are then added to the polymer melt. The extruder screw speed ranges from approximately 50 to approximately 500 rpm, preferably from 350 to 450 rpm.
[0008] The fire-resistant polyolefin prototype material according to the invention formula contains the following components, wt. %:
[0009] Ethylene vinyl acetate 18-23 Polypropylene copolymer 20-26 Fluoroelastomer 0.25-0,35 Ammonium polyphosphate, processed melamine and coated with aliphatic thermoplastic polymer, having terminal amino groups 35-50 Magnesium hydroxide 1-2 Alpha-olefin copolymer 0-15 N,N-ethylenebis-stearamide 0-2 Additional additives 0-5.
[0010] All five examples given in the patent use JLS PNP3D grade PFA, n>1000, which was treated with melamine and coated with a low molecular weight aliphatic thermoplastic polymer coating (in the range from 500 to 10,000 g / mol) having terminal amino groups. The CI of the material with a treated PFA content of 35 wt.% and achieving the required physical and mechanical properties of the material was 35.9-38.2%. With an increase in the content of treated PFA to 50 wt. The % CI of the material increased to 51.7%, but despite the introduction of additional ingredients: N,N-ethylenebis-stearamide (ADVAWAX 280) and paraffin wax OPE-AC-629A, the elongation at break value dropped sharply - the material became brittle (see examples 4 and 5 in tables 7 and 9 of the description of the prototype application).
[0011] The objective of the proposed invention is to develop a method for producing a fire-resistant polymer material based on thermoplastic ammonium polyphosphate, which, thanks to a fundamentally new approach to process technology, will make it possible to obtain a material with a predominant content of fire retardant, which will ensure high fire resistance characteristics and, at the same time, high deformability of the material.
[0012] The objective of the invention is also to create a fire-resistant polymer material that will have high fire resistance and at the same time high physical and mechanical characteristics.
[0013] The solution to the problem is achieved by the proposed:
[0014] - a method for producing a fire-resistant polymer material based on ammonium polyphosphate (APP), which includes mixing a melt of components in an extruder, in which, according to the invention, a mixture of PPA, degree of polymerization n=1250, and an organic polymer of ethylene vinyl acetate (EVA) is loaded into the extruder at a temperature of 200-230°C at a weight ratio of PPA:EVA = 2.33-4.00:1, mixed for 5-50 minutes at a rotation speed of the extruder screws of 50-100 rpm and the material is extruded in the form of a strand or granules.
[0015] The solution to the problem is also achieved by the proposed:
[0016] - a fire-resistant polymer material based on ammonium polyphosphate (PFA), obtained by the claimed method, consisting of high-molecular PFA with a degree of polymerization n=1250 and an organic polymer ethylene vinyl acetate, while the amount of PFA n=1250 in the material is 70-80 wt.%, and the material has the following characteristics: oxygen index 45-95%, tensile strength σp 0.7-3.6 MPa, relative elongation at tension 8.8-346.0%.
[0017] The use of PFA in the form of a melt in the proposed method makes it possible to increase the PFA content in the material to 80%, which ensures high fire resistance (FI up to 95%) while simultaneously providing high deformability of the resulting material, significantly exceeding the deformability of the flame-retardant materials currently used.
[0018] The proposed method was developed based on preliminary experimental studies of the thermoplastic properties of PFA and their mixtures with various organic polymers (Stegno E.V., Novikov V.A., Shaulov A.Yu. et al. Polymer mixtures of phosphorus and boron polyoxide. Polymers 2024: Proceedings of the XXV Scientific Conference of the Polymer and Composite Materials Department of the N.N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences. - M: TORUS PRESS, 2024, pp. 99-101). Previously, the effect of catalytic depolymerization of PFA by protons of -P-OH- groups formed during the release of ammonia from the ammonium group under conditions of shear deformations during extrusion mixing of PFA with organic polymers was discovered (Shaulov A.Yu., Vladimirov L.V. et al. / / Low-temperature phosphate composition. Bulletin of the Academy of Sciences. Chemical Series. No. 10, 2022. Pp. 2103-2107; A.Yu. Shaulov, A.V. Grachev et al.Ultralow Melting Ammonium Polyphosphate Compounds / / Glass Physics and Chemistry, 2024, Vol. 50, No. 1, pp. 61-67). Depolymerization of PFA is accompanied by the formation of low-molecular-weight thermoplastic products with low melt flow temperatures, which allows for an increase in the flame retardant content in the material while maintaining high deformation properties.
[0019] The figure shows thermomechanical curves reflecting the dependence of the softening temperature and flow rate on the composition of the mixtures obtained by extrusion mixing. The upper inflection points on the curves correspond to the softening temperatures of the mixtures, and the lower ones correspond to the temperatures at which the melts begin to flow. It can be seen from the figure that the original PFA n=1250 practically does not melt up to a temperature of 400°C (curve 4), whereas during extrusion mixing with CEVA the mixture softens already at 60°C (curves 2 and 3); the flow point for the PFA mixture n=1250 with CEVA is about 100°C. Curve 1 - thermomechanical properties of CEVA.
[0020] When studying the physical and mechanical properties of the resulting material, it was found that the highest deformation properties were achieved only with the flexible-chain polymer EVAH. Similar deformation values were not achieved with the other polymers studied, polyethylene and polystyrene.
[0021] The proposed method allows, when adding a mixture of PFA and an organic polymer to the extruder, to also introduce various additives or fillers, which will improve various properties of the resulting material.
[0022] It should be noted that the proposed method differs from the prototype by simplifying the process technology: a significant reduction in the number of components used and the elimination of the stage of preliminary processing of PFA.
[0023] Specimens for mechanical property testing were obtained by injection molding at 200-230°C and a pressure of 70 MPa; samples for determining the oxygen index were prepared by heat pressing at a temperature of 200-230°C and a pressure of 0.15 MPa.
[0024] We provide examples of the invention.
[0025] Example 1.
[0026] A mixture of 4.8 g of PFA is loaded in small portions into a twin-screw extruder at a temperature of 230°C at 100 rpm. n=1250 APP501 grade and 1.2 g of EVA28 grade VC590 (weight ratio of PFA to EVA = 4:1). The mixture is mixed for 5 minutes and the material is extruded into strands or granules. The PFA content in the material is 80% by weight. The test results of the resulting material are presented in the table.
[0027] Example 2.
[0028] A mixture of 4.9 g of PFA is loaded in small portions into a twin-screw extruder at a temperature of 230°C at 50 rpm. n=1250APP501 grade and 2.1 g of EVA28 grade VC590 (weight ratio of PFA to EVA = 2.33:1). The material is mixed for 50 minutes and extruded into strands or granules. The PFA content in the material is 70 wt.%. The test results of the resulting material are presented in Table 1.
[0029] Examples 3, 4.
[0030] The material is obtained similarly to Example 1 or 2, but instead of SEVA28, SEVA33 grade EVA EC33018 is used. The test results of the obtained material are presented in Table 1.
[0031]
[0032] Examples 5-8.
[0033] The material was obtained similarly to examples 1-4, but at a temperature of 200°C. The test results of the obtained material are presented in Table 2.
[0034]
[0035] Thus, the obtained results show that the proposed method for producing a fire-resistant polymer material, thanks to a fundamentally new approach to the technology of the component mixing process, makes it possible to obtain a material with high fire resistance characteristics (FI up to 95%) and, at the same time, high deformation properties.
Claims
1. A method for producing a fire-resistant polymer material based on ammonium polyphosphate (APP), comprising mixing a melt of components in an extruder, characterized in that a mixture of PPA, degree of polymerization n=1250, and an organic polymer of ethylene vinyl acetate (EVA) at a weight ratio of PPA:EVA=2.33-4.00:1 is loaded into the extruder at a temperature of 200-230°C, mixed for 5-50 min at a rotation speed of the extruder screws of 50-100 rpm, and the material is extruded in the form of a strand or granules.
2. A fire-resistant polymeric material based on ammonium polyphosphate (APP), characterized in that it is obtained by the method according to paragraph 1, consists of high-molecular PPA with a degree of polymerization n=1250 and an organic polymer of ethylene vinyl acetate, wherein the amount of PPA n=1250 in the material is 70-80 wt.%, and the material has the following characteristics: oxygen index 45-95%, tensile strength σ p 0.7-3.6 MPa, relative elongation at tension 8.8-346.0%.